Quantum chemical calculations of the reorganization energy of blue- copper proteins

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Quantum chemical calculations of the reorganization energy of blue- copper proteins. / Olsson, Mats H M; Ryde, Ulf; Roos, Björn O.

In: Protein Science, Vol. 7, No. 12, 12.1998, p. 2659-2668.

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Olsson, Mats H M ; Ryde, Ulf ; Roos, Björn O. / Quantum chemical calculations of the reorganization energy of blue- copper proteins. In: Protein Science. 1998 ; Vol. 7, No. 12. pp. 2659-2668.

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TY - JOUR

T1 - Quantum chemical calculations of the reorganization energy of blue- copper proteins

AU - Olsson, Mats H M

AU - Ryde, Ulf

AU - Roos, Björn O.

PY - 1998/12

Y1 - 1998/12

N2 - The inner-sphere reorganization energy for several copper complexes related to the active site in blue-copper protein has been calculated with the density functional B3LYP method. The best model of the blue-copper proteins, Cu(Im)2(SCH3)(S(CH'3)2)(0/+), has a self-exchange inner-sphere reorganization energy of 62 kJ/mol, which is at least 120 kJ/mol lower than for Cu(H2O)(+/2+)/4 This lowering of the reorganization energy is caused by the soft ligands in the blue-copper site, especially the cysteine thiolate and the methionine thioether groups. Soft ligands both make the potential surfaces of the complexes flatter and give rise to oxidized structures that are quite close to a tetrahedron (rather than tetragonal). Approximately half of the reorganization energy originates from changes in the copper-ligand bond lengths and half of this contribution comes from the Cu-S(Cys) bond. A tetragonal site, which is present in the rhombic type 1 blue-copper proteins, has a slightly higher (16 kJ/mol) inner-sphere reorganization energy than a trigonal site, present in the axial type I copper proteins. A site with the methionine ligand replaced by an amide group, as in stellacyanin, has an even higher reorganization energy, about 90 kJ/mol.

AB - The inner-sphere reorganization energy for several copper complexes related to the active site in blue-copper protein has been calculated with the density functional B3LYP method. The best model of the blue-copper proteins, Cu(Im)2(SCH3)(S(CH'3)2)(0/+), has a self-exchange inner-sphere reorganization energy of 62 kJ/mol, which is at least 120 kJ/mol lower than for Cu(H2O)(+/2+)/4 This lowering of the reorganization energy is caused by the soft ligands in the blue-copper site, especially the cysteine thiolate and the methionine thioether groups. Soft ligands both make the potential surfaces of the complexes flatter and give rise to oxidized structures that are quite close to a tetrahedron (rather than tetragonal). Approximately half of the reorganization energy originates from changes in the copper-ligand bond lengths and half of this contribution comes from the Cu-S(Cys) bond. A tetragonal site, which is present in the rhombic type 1 blue-copper proteins, has a slightly higher (16 kJ/mol) inner-sphere reorganization energy than a trigonal site, present in the axial type I copper proteins. A site with the methionine ligand replaced by an amide group, as in stellacyanin, has an even higher reorganization energy, about 90 kJ/mol.

KW - B3LYP method

KW - Blue-copper proteins

KW - Entatic state theory

KW - Induced-rack theory

KW - Reorganization energy

UR - http://www.scopus.com/inward/record.url?scp=0031700045&partnerID=8YFLogxK

U2 - 10.1002/pro.5560071220

DO - 10.1002/pro.5560071220

M3 - Article

C2 - 9865961

AN - SCOPUS:0031700045

VL - 7

SP - 2659

EP - 2668

JO - Protein Science

JF - Protein Science

SN - 1469-896X

IS - 12

ER -